pcie aka peripheral component
interconnect
express it replaced pci and replaced it
in two major ways
firstly it was a serial computer
expansion bus standard
whereas the original pci worked in
parallel with a total fixed bandwidth
amount
that is the more components that utilize
that bandwidth the slower its access
became french component per se
in the system as opposed to pcie which
if you added in more components
then sure the maximum bandwidth is still
there however the maximum bandwidth
would
ultimately be shared across all devices
pcie also carried with it a new slot
configuration
which comes in sizes of x1 x2 x4
x8 and x16 most games will use the x16
slot
available on their motherboard to power
their graphics card however
the pcie interface can also power hard
drives ssds
wi-fi and ethernet connections though
here is where the fun starts
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back to the video
pcie which was introduced 17 years ago
in 2003
has gone through generations of
improvements starting with of course
gen 1 with an x16 slot or 16 lane
configuration
supporting speeds of four gigabytes per
second both ways
in other words eight gigabytes in total
read it right and this was polled at 2.5
gigahertz
now this polling is very important this
is what we're going to talk about later
with the rtx 3090
and the results next in the improvement
tier was pcie gen2 sporting doubled the
polling rates at five gigahertz and
doubled the transfers at eight gigabytes
per second each way
for 16 gigabytes in total pcie gen 3
essentially doubled the transfers yet
again
for 32 gigabytes in total and the
polling rates were at 8 gigahertz
now pci gen 4 which was introduced to
the mainstream gamer by
amd with their x570 motherboard launch
supports 64 gigabytes per second
and a polling rate of 16 gigahertz pcie
gen 5 which will be later released in
the future
will then double the speeds of pci gen
4.
so how much bandwidth does your graphics
card exactly need
and say for instance you're a 4k gamer
will something like pcie
gen 3 suffice well graphics cards or as
i like to call them gravis cards
work with 32-bit color this 32-bit color
mode
at 4k 30fps for example requires
approximately one gigabyte per second
transfers
double that to 60 fps 2 gigabytes per
second
120fps 4k gaming that will need 4
gigabytes per second transfers
however these are only approximations to
understand how much bandwidth a gamer
actually needs
so in theory even a pca gen2 x16 slot
is more than enough for an rtx 3090
overclocked
right well actually yes
starting off with the games the numbers
and the benchmarks our test system
consists of an i9 10 900 k
for pca gen 2 and gen 3 tests and then
on the amd side we're using a 3950x
for pci gen 4 tests since the intel side
doesn't have dn4 support from the cpu
just yet
but both these cpus were used with 3600
megahertz cl 16 memory
to ensure that the rtx 3090 would be
pegged near 100
gpu utilization as much as possible go
on to the numbers
here we can see that shadow of the tomb
raider pcie gen 2
x 16 was coming awfully close to the
successors gen 3 and 4
at x 16 speeds though limiting the gen 3
bandwidth to x4
showed that this rtx 3090 that was
overclocked was starting to power
through these limits
though not by a whole lot horizon zero
dawn showed a pretty similar trend
though it was slightly more in favor of
having more bandwidth available
do maternal very similar showing the pca
gen 3
x4 similar to gen 2 x8 and of course the
og
gen 1x16 was reaching its limits here
the division 2
yep nothing to see here folks and then
lastly modern warfare
same scenario as before however testing
1080p on the flip side
showed an identical trend to the other
games at 4k
so basically summing it up gen 2x16
is more than enough for even an rtx 3090
overclocked
in 2020 though you may have noticed that
gen 3x16 on the intel side of things
was beating gen 2x16 by slightly better
margins in all titles
and you may be wondering why is this
well this has to do with what i believe
is the polling rates
and we hinted at this earlier but
basically the difference between five
gigahertz and eight gigahertz is a sixty
percent increase in the polling rates
so the cpu pulls the gpu shader
essentially faster
giving that slight increase that you see
in the fps numbers
gen 4 if we were to theoretically put
this on the intel side of things
this would in turn give us slightly more
fps as well
but it would start suffering
significantly from diminishing returns
an easy way to help conceptualize this
is to just look at polling rates on mice
where razer for example wants to go from
a thousand hertz
with an average of 0.5 milliseconds
delay polling all the way up to 8 000
hertz an 8-fold increase in polling
rates but only an absolute drop
in 0.4375 milliseconds
average as opposed to say 1 000 hertz
versus 125 hertz we have a much larger
drop in absolute average delay
of roughly three and a half milliseconds
average if you're trying to figure out
the math just think that some poles will
hit the start of the wave and some will
hit at the very end hence why it
averages out
and so there it is with rtx 3090s if you
want to put these in sli
overclock them on gen 3x8 slots
it's going to be absolutely fine though
i really don't think your wallet would
be
however these results were ultimately a
big surprise for me personally
i thought the rtx 3090 would require a
bit more bandwidth but the numbers and
testing always paints the biggest
picture so keep in mind although you
won't need to seriously worry about pcie
bandwidth for gaming for
some years to come even on a gen 3x16
motherboard
what if there was a revolutionary
breakthrough in the way that your
motherboard and computer graphics were
processed
well you'd probably just go out and buy
a new motherboard with the latest and
greatest pcie gen
6.9 so there it is with pcie gen 3
versus gen
4. it's nothing to worry about on any
modern day graphics card
through an x16 slot and in fact gen 2x16
is still okay so currently the biggest
difference between pcie gen 3 and gen 4
is actually i believe on the nvme side
of things where the x4 slots
do gain a lot more speeds on pca gen 4
motherboards
where you've got those higher speed ssds
running at higher speeds because the
throughput is ultimately doubled going
from gen 3x4 to gen 4x4
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bye
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